WASHINGTON (Reuters) - The ouster of Attorney General Jeff Sessions by President Donald Trump on Wednesday drew immediate criticism from Democrats who warned Trump against moving to squash a probe of Russian meddling in the 2016 U.S. presidential election.

The probe, led by Special Counsel Robert Mueller under the supervision of the Justice Department, has clouded the Trump presidency. The president had long complained about Sessions recusing himself from supervising Mueller.

The removal of the top U.S. law enforcement officer raised questions among Democrats concerned about the acting replacement Trump named for Sessions and what moves might follow.

“Congress must take bipartisan action to protect the integrity of Special Counsel Mueller’s investigation,” said No. 2 House of Representatives Democrat Steny Hoyer, hours after Democrats won a House majority in Tuesday’s elections.

If Sessions’ departure was an “opening move” by Trump to meddle in Mueller’s investigation, Hoyer said in a statement, “the president must be held accountable.”

A Justice Department spokeswoman, asked if Sessions’ acting replacement, Matthew Whitaker, would now oversee Mueller, replied: “The acting attorney general is in charge of all matters under the purview of the Department of Justice.”

A spokesman for Mueller’s office declined to comment on Sessions’ departure and what it means for Mueller’s probe.

Trump’s personal lawyer Rudy Giuliani told Reuters on Tuesday that he assumed it was “not going to affect” the Mueller investigation.

RECUSAL DEMAND

In a Twitter message, the medium he often uses for dismissing subordinates, Trump said he had replaced Sessions with Whitaker, who will be acting attorney general. Whitaker had previously been Sessions’ chief of staff.

Sessions said in a letter to Trump that he had resigned at the president’s request.

Some Democrats quickly demanded that Whitaker, as well, should recuse himself from supervising Mueller, as Sessions did.

“Given his previous comments advocating defunding and imposing limitations on the Mueller investigation, Mr. Whitaker should recuse himself from its oversight for the duration of his time as acting attorney general,” Senate Democratic leader Chuck Schumer said in a statement.

In August 2017, Whitaker wrote an opinion piece for CNN, titled “Mueller’s investigation of Trump is going too far.” In it, he said Mueller had too much latitude in his investigation of Russian activities during the 2016 election battle and any possible collusion with Moscow by the Trump campaign.

Sessions said in a letter to Trump that he had resigned at the president’s request.

Some Democrats quickly demanded that Whitaker, as well, should recuse himself from supervising Mueller, as Sessions did.

“Given his previous comments advocating defunding and imposing limitations on the Mueller investigation, Mr. Whitaker should recuse himself from its oversight for the duration of his time as acting attorney general,” Senate Democratic leader Chuck Schumer said in a statement.

In August 2017, Whitaker wrote an opinion piece for CNN, titled “Mueller’s investigation of Trump is going too far.” In it, he said Mueller had too much latitude in his investigation of Russian activities during the 2016 election battle and any possible collusion with Moscow by the Trump campaign.

“Under Acting Attorney General Matthew Whitaker, it is imperative that the important work of the Justice Department continues, and that the Mueller investigation proceeds to its conclusion unimpeded,” he said on Twitter.

HARSH ATTACKS

Never in modern history has a president attacked a Cabinet member as frequently and harshly in public as Trump did Sessions, 71, who had been one of the first members of Congress to back his presidential campaign in 2015.

Trump was only a few weeks into his presidency in March 2017 when Sessions upset him. Rejecting White House pleas not to do so, Sessions stepped aside from overseeing an FBI probe of potential collusion between the Trump campaign and Moscow, citing news reports of previously undisclosed meetings he had with Russia’s ambassador to Washington for his recusal.

Deputy Attorney General Rod Rosenstein took over supervision of the Russia investigation. He appointed Mueller in May 2017 as the Justice Department’s special counsel to take control of the FBI’s Russia probe after Trump fired FBI Director James Comey.

A permanent replacement for Sessions must be confirmed by the Senate, which Trump’s Republicans will continue to control as a result of Tuesday’s midterm elections.

Mueller is pursuing an investigation into whether Trump’s campaign colluded with Russia, whether Trump unlawfully tried to obstruct the probe, and possible financial misconduct by Trump’s family and associates. Mueller has brought charges against Trump’s former campaign chairman and other campaign figures, as well as against 25 Russians and three firms accused of meddling in the campaign to help Trump win.

Trump has denied his campaign colluded with Russia.

Reporting by Sarah N. Lynch; Writing by Bill Trott and Kevin Drawbaugh; Editing by Will Dunham and Peter Cooney